Small Craft Advisory 184, NWS Juneau, AK

023 
FZAK51 PAJK 261214
CWFAJK

Coastal Waters Forecast for Southeast Alaska
National Weather Service Juneau AK
414 AM AKDT Fri Mar 26 2021

Southeast Alaska Inside Waters from Dixon Entrance to Skagway

Wind forecasts reflect the predominant speed and direction
expected. Sea forecasts represent the average of the highest
one-third of the combined windwave and swell height.

PKZ098-270300-
414 AM AKDT Fri Mar 26 2021
.SYNOPSIS FOR SOUTHEAST ALASKA INNER CHANNELS COASTAL WATERS...
A broad area of low pressure remains in the northern gulf while 
higher pressure persists across the North Pacific. A wave of low 
pressure develops in the southern gulf Friday, then tracks towards
the eastern gulf coast early Saturday. 

$$

PKZ011-270300-
Glacier Bay-
414 AM AKDT Fri Mar 26 2021

.TODAY...SE wind 10 kt. Seas 2 ft or less. Rain and snow. 
.TONIGHT...SE wind 10 kt. Seas 2 ft or less. Rain showers late. 
.SAT...NW wind 10 kt becoming SE in the afternoon. Seas 2 ft
or less. 
.SAT NIGHT...NW wind 15 kt. Seas 3 ft. 
.SUN...W wind 10 kt becoming light. Seas 2 ft or less. 
.MON...Light winds. Seas 2 ft or less. 
.TUE...Light winds becoming S 10 kt. Seas 2 ft or less. 

$$

PKZ012-270300-
Northern Lynn Canal-
414 AM AKDT Fri Mar 26 2021

...SMALL CRAFT ADVISORY THROUGH THIS AFTERNOON...

.TODAY...SE wind 25 kt. Gusts to 40 kt. Seas 5 ft. Rain.
.TONIGHT...SE wind 20 kt. Seas 4 ft. Rain and snow showers.
.SAT...N wind 10 kt becoming S 20 kt in the afternoon. Seas
building to 4 ft in the afternoon. 
.SAT NIGHT...N wind 25 kt. Gusts to 40 kt. Seas 5 ft. 
.SUN...N wind 25 kt diminishing to 10 kt. Seas 5 ft subsiding to 
2 ft or less. 
.MON...S wind 10 kt. Seas 2 ft or less. 
.TUE...S wind 15 kt. Seas 3 ft. 

$$

PKZ013-270300-
Southern Lynn Canal-
414 AM AKDT Fri Mar 26 2021

.TODAY...SE wind 20 kt. Gusts to 35 kt. Seas 4 ft. Rain.
.TONIGHT...SE wind 20 kt. Gusts to 35 kt in the evening. Seas
4 ft. Rain.
.SAT...N wind 10 kt becoming S 20 kt in the afternoon. Seas
building to 4 ft in the afternoon. 
.SAT NIGHT...S wind 20 kt. Gusts to 35 kt. Seas 4 ft.
.SUN...N wind 15 kt. Seas 3 ft subsiding to 2 ft or less. 
.MON...S wind 15 kt. Seas 3 ft. 
.TUE...S wind 15 kt. Seas 3 ft. 

$$

PKZ021-270300-
Icy Strait-
414 AM AKDT Fri Mar 26 2021

.TODAY...SE wind 15 kt. Seas 3 ft. Rain in the morning. 
.TONIGHT...SE wind 15 kt. Seas 3 ft. Rain showers.
.SAT...E wind 10 kt becoming W 15 kt in the afternoon. Seas
building to 3 ft in the afternoon. 
.SAT NIGHT...W wind 15 kt. Seas 3 ft. 
.SUN...W wind 10 kt. Seas 2 ft or less. 
.MON...SW wind 10 kt. Seas 2 ft or less. 
.TUE...S wind 10 kt. Seas 2 ft or less. 

$$

PKZ022-270300-
Cross Sound-
414 AM AKDT Fri Mar 26 2021

.TODAY...SW wind 15 kt. Seas 7 ft. Rain in the morning. 
.TONIGHT...SW wind 15 kt. Seas 6 ft. Rain showers. 
.SAT...N wind 10 kt becoming W 20 kt in the afternoon. Seas
5 ft building to 8 ft in the afternoon. 
.SAT NIGHT...W wind 15 kt. Seas 7 ft. 
.SUN...NE wind 10 kt becoming W. Seas 9 ft. 
.MON...W wind 15 kt. Seas 10 ft. 
.TUE...SW wind 15 kt. Seas 11 ft. 

$$

PKZ031-270300-
Stephens Passage-
414 AM AKDT Fri Mar 26 2021

.TODAY...SE wind 15 kt. Gusts to 35 kt early in the morning. Seas
3 ft. Rain.
.TONIGHT...SE wind 15 kt. Seas 3 ft. Rain.
.SAT...S wind 10 kt. Seas 2 ft or less. Rain.
.SAT NIGHT...S wind 10 kt. Seas 2 ft or less. 
.SUN...N wind 10 kt. Seas 2 ft or less. 
.MON...S wind 15 kt. Seas building to 3 ft. 
.TUE...S wind 15 kt. Seas 3 ft. 

$$

PKZ032-270300-
Northern Chatham Strait-
414 AM AKDT Fri Mar 26 2021

.TODAY...S wind 15 kt. Seas 3 ft. 
.TONIGHT...S wind 15 kt. Seas 3 ft. Rain late. 
.SAT...S wind 10 kt becoming NW in the afternoon. Seas
2 ft or less. Rain showers in the morning. 
.SAT NIGHT...S wind 10 kt. Seas 2 ft or less. 
.SUN...N wind 10 kt becoming light. Seas 2 ft or less. 
.MON...S wind 10 kt. Seas 2 ft or less. 
.TUE...S wind 10 kt. Seas 2 ft or less. 

$$

PKZ033-270300-
Southern Chatham Strait-
414 AM AKDT Fri Mar 26 2021

.TODAY...S wind 10 kt. Seas 2 ft or less, except 5 ft near ocean
entrances. 
.TONIGHT...S wind 15 kt. Seas 3 ft. Near ocean entrances, seas 7 
ft. Rain.
.SAT...S wind 10 kt becoming NW in the afternoon. Seas 2 ft
or less, except 8 ft near ocean entrances. 
.SAT NIGHT...SW wind 10 kt. Seas 2 ft or less, except 7 ft
near ocean entrances. 
.SUN...NW wind 10 kt. Seas 2 ft or less. 
.MON...W wind 10 kt. Seas 2 ft or less. 
.TUE...SW wind 10 kt. Seas 2 ft or less. 

$$

PKZ034-270300-
Frederick Sound-
414 AM AKDT Fri Mar 26 2021

.TODAY...SE wind 10 kt. Seas 2 ft or less.
.TONIGHT...S wind 15 kt. Seas 3 ft. Rain late. 
.SAT...S wind 10 kt becoming W in the afternoon. Seas 2 ft
or less. Rain.
.SAT NIGHT...SW wind 10 kt. Seas 2 ft or less. 
.SUN...NW wind 10 kt. Seas 2 ft or less. 
.MON...Light winds becoming S 15 kt. Seas building to 3 ft. 
.TUE...S wind 15 kt. Seas 3 ft. 

$$

PKZ035-270300-
Sumner Strait-
414 AM AKDT Fri Mar 26 2021

.TODAY...SE wind 10 kt. Seas 2 ft or less. Rain.
.TONIGHT...S wind 20 kt. Seas 4 ft. Rain.
.SAT...S wind 25 kt becoming SW 15 kt in the afternoon. Seas
4 ft, except 6 ft near ocean entrances. Rain in the morning. 
.SAT NIGHT...SW wind 10 kt. Seas 2 ft or less, except 5 ft
near ocean entrances. 
.SUN...NW wind 10 kt. Seas 2 ft or less. 
.MON...SW wind 10 kt. Seas 2 ft or less. 
.TUE...SW wind 15 kt. Seas 3 ft. 

$$

PKZ036-270300-
Clarence Strait-
414 AM AKDT Fri Mar 26 2021

.TODAY...S wind 20 kt. Seas 4 ft. Rain.
.TONIGHT...S wind 20 kt. Seas 4 ft. Rain.
.SAT...SE wind 25 kt. Seas 8 ft. Rain.
.SAT NIGHT...NW wind 10 kt. Seas 5 ft. 
.SUN...NW wind 15 kt. Seas 3 ft. 
.MON...W wind 15 kt becoming SE. Seas 3 ft. 
.TUE...S wind 15 kt. Seas building to 3 ft. 

$$

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
256 PM AKDT Thu Mar 25 2021

.SHORT TERM...Precipitation is settling over the area this afternoon under backing
onshore flow. A developing surface low over the northern gulf has
focused the precip over the northern panhandle today, with snow
falling from Yakutat to Skagway and south to Gustavus. Temperatures
are gradually rising, causing more of a mix or for rain to become
the dominate p-type. Accumulations tonight look to be 2 inches or
less for places like Haines, Skagway and White Pass. Otherwise the
mixing and change over to rain will melt what has fallen.

Split flow will be the forecast challenge the next two days. The
northern gulf low and subsequent troughs moving out of the Alaska
interior will bring in a colder airmass across the north. Meanwhile,
a W-SW jet will become directed at the southern panhandle tonight,
with a warmer airmass. This pseudo atmospheric river will remain
directed over the south through Saturday morning. Over the next 2
days, total qpf should be around 2", so nothing that that area
isn't used to.

Models and Ensembles have been hinting at a surface wave
developing along the sharp thermal boundary stretched across the
gulf late Friday into Saturday. With good agreement among the
guidance, decided to add this feature to the forecast. There are
still slight discrepancies on the exact track of this feature;
however a blend of the EC/GFS/NAM provided a reasonable solution
showing the weak low moving NE towards Baranof Island, then onward
into BC. Flipped winds around to the north from Icy Strait
northward for Saturday morning as the low passes by. Will have to
keep an eye on P-type as this low track is historically good for
accumulating snow for Juneau and the Icy Strait corridor.
Currently thinking little in the way of accumulations as
temperatures may be just warm enough to prevent snow from
sticking. Will have to monitor this feature over the next day or
so for possible changes to the forecast. This surface wave also
has the potential to increase precipitation amounts and rates
across the southern 2/3 of the Panhandle as well.

Winds across Southeast Alaska are expected to remain below small
craft levels with the exceptions of Lynn Canal and Clarence
Strait. Small crafts are expected to develop in Northern Lynn
tonight and persist through Friday. As the weak surface wave moves
into the Panhandle on Saturday, expect an increase in southerly
winds across the Southern Inner Channels as well. Bumped up winds
to small craft levels for Clarence Strait Saturday morning and
afternoon. Winds are expected to weaken and flip around to the
north for most places Saturday night into Sunday morning as the
low departs the region and a northerly gradient sets up.

Overall forecast confidence is around average. Lower confidence
exists regarding the finer details of the weak surface low
Saturday morning.

.LONG TERM.../Saturday through Friday as of 10PM Wednesday/...The
moisture supply for the weekend system look to be less impressive
and looks like it will take a more southerly track closer to the
Dixon Entrance than we have been seeing from the models. Model
forecast IVT values also look to be decreasing to levels that are
much less impressive that mainly remain offshore, as well. A
break between systems from Sunday into Monday with decreased
cloudiness and decreased winds will come after the previous system
moves away from the southern Panhandle. This will be caused by a
decently strong ridge of high pressure building/pushing eastward
through the eastern Gulf and Panhandle and will last for about a
day or so until a weak low begins to move into the Panhandle
Monday afternoon. Patchy fog will be a possibility for many areas
that see prolonged clearing and light winds for the northwest
Panhandle Saturday night and for the rest of the Panhandle Sunday
night as the clearing skies move southeastward before the low
moves in.

The Juneau area and the central/northern Panhandle look to be
near the borderline of rain and snow for all of the systems
through the end of the period, especially near the beginning of
the event that happens after the ridge moves out of the area as
we will have had decreased cloudiness and light winds the night
before, giving us good radiational cooling throughout the majority
of the Panhandle. Therefore, precipitation may start out as
purely snow and transition over to a wintry mix or strait rain
later on in the day for the central Panhandle as surface
temperatures warm. Model thickness values look to be in the
borderline range, as well, for the aforementioned area. We also
look to be just on the colder side of the jet with these systems.

It looks like temperatures may not end up warming up quite as
much on average for the weekend as it looked like it would over
the past few days. Since the weekend system is not as strong and
tracks much farther south, it looks like it won't be bringing as
much warm air advection into the Panhandle with it. This can be
seen in the model forecast 850 mb temperatures.

Generally, with the diurnal temperature curve that the models
want to put into the temperature forecast as we are seeing much
more sun than we've generally seen throughout the winter, it is a
possibility that we may have a nighttime snow / daytime rain
situation for areas around the central Panhandle.

A much stronger frontal system, looks like it will move in just
behind Monday's weak low, giving us little to no break from the
active weather. The exact positioning and strength of this system
is still a bit up in the air as this system is still about a week
away from any significant impact in our region. It does look like
it has the potential to bring some enhanced winds and seas and
bring a good amount of precipitation, though.

As for winds, some small crafts were added to Lynn canal and the
central and southern Gulf areas in general preparation as the
pressure gradient tightens as these systems approach.

Operational model agreement was very good in general for the vast
majority of the long term forecast period. Therefore, confidence
for the long term forecast period is good.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ012-013-022-041>043-051-052.

&&

Ferrin/CM/JLC

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